Looking for another angle, we perused the help file
for the OOPIC programming. As it turns out, there was an
object dedicated to the SRF-04. The help file also gave
example code in BASIC syntax, but once we knew how to
call the object we were able to translate the rest. When
the program compiled properly, we knew we were on to
something, and we set out to test a simple program.

Our simple obstacle avoidance program would instruct
the robot to rove around, pinging the ultrasonic sensor.
Once the sensor detected an object at a certain range (in
our case, we set that range at 30 cm), the robot would
turn to the right to avoid the obstacle. We put down
some obstacles for the bot to avoid. The Spark
gearmotors took the bot careening towards our obstacle,
but at 30 cm away the bot took an abrupt turn and went
on its jolly way.

Now that we had the Cobra down to its fighting
weight, we also wanted to test its Sumo strength. We
started out with some weighty obstacles (books) and an
obstacle detection program to ensure that the SRF-05
didn’t promote avoidant behavior. The bot pushed around
even a stack of heavy books with no problem, and that
got us thinking about how this bot had a certain calling
that transcended electronics experimentation and pushing
around books.

After our frolic with the ultrasonic sensor, we realized
that we had not yet used the Cobra chassis for its
intended purpose — mini Sumo domination. Unfortunately,
its natural foe would be our other mini Sumo robot: the
Mark III. The Mark III, however, was missing a few key
parts and was in no shape to compete. Fortunately, we
had a menagerie of other robots ready to jump into the
ring. Calling in particular on our Sensor Olympics
competitors, it was no surprise when the Cobra toppled
the OLLO bug and scooped the larger Scribbler right out
of the field. The combination of the high friction wheels
and low center of gravity was deadly indeed.

Cobra Commander

This is all somewhat expected, given the original
motivations and goals of the Cobra’s design. We got in
touch with Fingertech Robotics’ Kurtis Wanner to learn
more about the genesis of the kit, and to see if our
digression with sensor experimentation was an intended
use of the kit or simply a happy byproduct.

As it turns out, we think the initial motivation behind
the Cobra does help lend the kit nicely to electronics
experimentation. The goal of the Cobra was to help take
some of the mechanical guesswork out of building a mini
Sumo robot for competitors that were more expert in
electronic and programming that designing mechanical

Special Thanks to

Kurtis Wanner

The Cobra Strikes Again

A RIVALRY FOR THE AGES.

bits like drive trains.

The Cobra was designed to give builders the best
mechanical base possible with its powerful motors and
low CG. The Cobra was quite a hit with college students
in Saskatoon and at a high school level event called
myRobotRumble sponsored by the Saskatchewan Institute
of Applied Science and Technology (where a Parallax
control board paired with the Cobra like a nice red wine
and a delicious steak).

We asked Kurtis if the Cobra was also designed with
electronics experimentation in mind, and we were mildly
surprised that mini Sumo was really the exclusive focus of
the kit. The idea of a platform for experimentation
conjured up images for Kurtis of large lumbering robots,
beasts of burden that could carry around large arrays of
data gathering technology. We suppose that such an
impression is natural. If we challenge ourselves to visualize
an archetypal platform for experimentation, we see
something like the behemoths of the DARPA Grand
Challenge.

At the same time, though, we think one of the
prototypical aspects of an electronics experimentation
platform is that it takes all of the guesswork out of the
mechanical aspect of the bot, letting the tinkerer focus on
electrical and software issues. We feel like that is exactly
what the Cobra chassis allowed us to do when figuring
out the SRF-05.

Just as the Cobra evolved over the course of these
two articles, Kurtis and the folks at Fingertech are intent
upon helping the kit continuously improve. In fact, they’re
already working on pretty much everything that gave us
pause as we worked on the kit. They’re working on some
frame adapter bits to make sure that any brain can be
easily accommodated.

Last time, we were also a little wary about the glued-on motors, but we have been assured that the glue
sets in a CNC’d jig, and that the setting is super solid.
We think that sort of commitment to excellence bodes
very well for the success of the Cobra inside and outside
of the dohyo. SV